A TCP protocol at a transport layer plays an important role, i.e., congestion control, for ensuring accurate data transmission between a source node that generates and transmits data and a destination node that finally receives the data. In most of conventional TCP congestion control techniques, at the source node, presence or absence of congestion is determined and the congestion is controlled.
Most of congestion situations occur at a wireless router or a wireless AP having both wired and wireless environments. This is because a wired device has a higher data rate than a wireless device, and, thus, the throughput in a wireless network cannot be equal to the throughput in a wired network. Traditional congestion control mechanisms were suggested long before commercialization of a wireless network technique. Therefore, at the present time where a wireless internet usage rate has been rapidly increased by using smart devices, new techniques for solving the problems of the previously suggested techniques have been suggested. As such, it becomes very important to improve performance of a congestion control technique in a TCP communication.
In most of conventional TCP congestion control techniques, at the source node that generates and transmits a packet, presence or absence of congestion is determined and the congestion is controlled. Since the source node is a starting point for transmitting a packet, it may be efficient to directly determine presence or absence of congestion and control the congestion at the source node.
However, since network congestion is highly likely to occur at the wireless AP or router positioned between the source node and the destination node, a congestion level cannot be accurately determined by using only the above-described technique. Further, an effect of congestion control based on an inaccurate determination result is insignificant. Therefore, it may be more efficient to detect presence or absence of congestion at the destination node directly affected from the wireless AP or router.
Meanwhile, a conventional congestion control technique mainly using only the destination node has a problem that a control instruction needs to be transmitted from the destination node to the source node. This incurs additional cost, and the existing TCP standards need to be greatly changed in order to avoid such a problem.
In this regard, Korean Patent No. 10-0895182 (entitled “Transport control method of wireless communication system”) describes a technique about a TCP.